1. Technical Field
The present invention relates to a liquid crystal device, an electronic apparatus, and a method of manufacturing a liquid crystal device.
2. Related Art
As a means for achieving a wide viewing angle of a liquid crystal device, an IPS (In-Plane Switching) mode, which is one example of a so-called lateral electric field mode, has been put into practical use, in which an electric field is generated in an in-plane direction (lateral direction) to a substrate, the lateral electric field causes liquid crystal molecules contained in a liquid crystal layer to be rotated in a plane parallel of the substrate, thus controlling the transmission of light. Further, an FFS (Fringe-Field Switching) mode is proposed as an improvement of the IPS mode.
Such a lateral electric field mode liquid crystal device has a configuration in which electrodes such as common electrodes and pixel electrodes or conductive members such as wirings are arranged on an element substrate having formed thereon driving elements such as TFT (thin film transistors), whereas conductive members are not arranged on a counter substrate which is disposed close to the display surface. For this reason, there is a problem in terms of display quality in that such a liquid crystal device is likely to be affected by electric fields (external electric fields) from outside of the counter substrate, typically static electricity, and thus, irregularities in the liquid crystal display are likely to occur. In order to solve such a problem, a method has been proposed in which an electrostatic shielding layer formed of a transparent conductive film is formed on the side of the counter substrate so that static electricity is trapped in the electrostatic shielding layer, thereby preventing display irregularities (see JP-A-2001-051263, for example).
JP-A-2001-051263 discloses a configuration of the counter substrate in which the electrostatic shielding layer is provided on the outer side (the side opposite to the liquid crystal layer) of the glass substrate and a configuration in which the electrostatic shielding layer is provided on the inner side (the side of the liquid crystal layer) of the glass substrate. When the two configurations are compared, the counter substrate having the electrostatic shielding layer on the inner side thereof has an advantage of being easy to manufacture because the electrostatic shielding layer can be formed by being laminated on members provided on the inner side such as an alignment film, and it is thus not necessary to reverse the glass substrate.
In recent years, there has been an increasing demand for achieving a thin liquid crystal device, and in order to comply with such a demand, a pair of substrates (later-described element substrate and counter substrate) sandwiching the liquid crystal layer is often polished to achieve a small thickness. Such a polishing step is performed after the pair of substrates is bonded together by a sealing member so as to face each other. As described above, in the case of arranging the electrostatic shielding layer on the outer surface, since the electrostatic shielding layer cannot be arranged prior to the polishing step, anti-static electricity measures are insufficient in the previous steps of the polishing step.
The electrostatic shielding layer is obtained by forming an electrostatic shielding layer from ITO (indium tin oxide alloys) under high-temperature and in a vacuum. When the electrostatic shielding layer is arranged after the polishing step, namely after the pair of substrates is bonded together, the element substrate and the counter substrate are exposed to the high-temperature in a vacuum, the forming material (typically, resin) of the sealing member or a color filter layer may be deteriorated or peelings may occur at the interface or the inside of the resin. For this reason, in the configuration of having the electrostatic shielding layer at the outer side of the glass substrate of the counter substrate, it is difficult to achieve the anti-static electricity measures (namely, the improvement in the display quality) and a small thickness of the liquid crystal device. Therefore, the configuration of having the electrostatic shielding layer at the inner side of the counter substrate is advantageous. That is to say, by performing the polishing step after bonding the pair of substrates together, it is possible to achieve a small thickness of the liquid crystal device and improve the display quality.
However, JP-A-2001-051263 discloses a structure in which the electrostatic shielding layer is formed at the back surface of an alignment film on the side of the counter substrate as an example of the configuration having the electrostatic shielding layer at the inner side of the glass substrate. When the electrostatic shielding layer is provided at such a position, only the alignment film is present between the electrostatic shielding layer and the liquid crystal layer, and thus, the distance between them decreases. For this reason, a vertical electric field is generated between the electrostatic shielding layer for trapping static electricity and the pixel electrodes or the common electrodes provided on the element substrate, thus disadvantageously disturbing the lateral electric field mode driving. Therefore, the anti-static electricity measures of the liquid crystal device are insufficient.
In order to cope with such circumstances, a liquid crystal device according to a comparative example is proposed as described below. FIG. 5 is a schematic cross-sectional view of a liquid crystal device 3 according to the comparative example. The liquid crystal device 3 has a similar configuration as the liquid crystal device according to later-described respective embodiments, and most of the constituent elements are the same. The descriptions of the respective constituent elements will be provided later, and the arrangement of the electrostatic shielding layer will be described.
As illustrated in the drawing, in the liquid crystal device 3, an electrostatic shielding layer 40 is directly formed as the first layer on a counter substrate body 21 without via any intervening layer. Since there is no underlying layer, it is practically impossible to form an alignment mark in advance and it is thus difficult to apply a mask film forming method that positions a mask on the counter substrate body 21 to form a film on a local area of the counter substrate body 21. Therefore, the electrostatic shielding layer 40 is formed on the entire surface of the counter substrate body 21 in a so-called beta form. When the electrostatic shielding layer 40 is formed in the beta form, the end face of the counter substrate body 21 becomes even with the end face of the electrostatic shielding layer 40 at the end portion B of the counter substrate 20. That is to say, the end face of the counter substrate body 21 and the end face of the electrostatic shielding layer 40 become identical to each other in a plan view. In the case of having such a shape, namely when the end faces are even with each other, static electricity can easily enter and the corrosion of the electrostatic shielding layer 40 is likely to occur.